How Doctors Think

A recently published book of the same title, by Dr. Jerome Groopman of Harvard Medical School, is a must-read not only for physicians, but for anybody who ever came in contact with the medical profession—and that’s all of us.

Dr. Groopman, having been himself a patient and a cancer survivor, examined in depth the sources of the all too frequent medical errors that afflict the profession. I would probably do only partial justice to his observations if I summarized the two root causes of medical errors:

Patient overload, and limited time to really think, yes think, about the patient and the problem at hand.

Partially, as a result of 1, doctors make snap judgments on the basis of first impression, or gestalt.

I will cite two examples from the book.

Dr. Groopman developed pain that got progressively worse with time. He visited four orthopedic hand specialists. Mind you, they all knew Dr. Groopman as a Professor of Medicine at Harvard, so one would expect above average thoughtfulness in making a diagnosis and suggesting a course of treatment. The first one swept into the room, half-listened to the patient’s complaint, took a quick look at the hand, made the diagnosis, and was ready to schedule surgery. The second and the third were essentially a repeat performance of the first one, except the diagnoses varied from the first one, and from each other’s. One of those was absolutely wild; gout in the hand. Now mind you, gout is a disease where crystals of uric acid, when they reach very high concentrations in the blood, precipitate in soft tissues that are colder relative to the rest of the body. This is why 99% of the time, they precipitate in the large toe, the farthest point from the heart. How did the “specialist” arrive at such a diagnosis, without even asking the patient if he had a history of gout or pain in his toe, or ordering a blood test to measure his uric acid level? Is it sheer incompetence? Maybe. But weirder things happen when your patient is the 70th you have seen in 12 hours (about five minutes per patient). To Dr. Groopman’s question of one of the orthopedists, what if your diagnosis is wrong? The answer was astounding: No big deal, we’ll find out during surgery. Only the fourth orthopedist, who was just as pressed for time, did the obvious thing: He asked the patient to move his fingers and observed the tendon where the pain was located.

The other specialty examined by Dr. Groopman is Radiology.

“Radiology is a discipline broken down into two processes: the process of perception and the process of cognition.”

This means that first, the radiologist must make an observation; second, he needs to analyze what he perceives, what it means, and the possible explanations for the finding. Like primary care physicians, he is at risk to miss something significant in the blur—a change in contour of a tissue or a variation in the density of an organ that he needs to notice. But the sheer volume of images a radiologist has to examine in a day’s work can easily cause a lapse in concentration. If we assume about an average of 30 seconds per image, a lapse of a few seconds can result in a missed finding and a wrong diagnosis.

Gestalt: What’s wrong with it?

Medical students and Radiology trainees are taught to systematically inspect each anatomic component on the x-ray. But radiologists are expected to look at an image and analyze it very quickly. Conclusions from the first impression, or “gestalt”, are supposed to be the mark of good training. Indeed, many radiologists rely heavily on gestalt, rapidly distinguishing normal from abnormal, drawing conclusions within seconds of viewing an image.

To compound the problem, another human foible enters into the equation: the seduction of search satisfaction. If a patient is referred with the typical findings of fever, cough, and yellow sputum, the radiologist’s attention is quite humanly focused on the lungs in his search for the expected pneumonia. Once the radiologist determines that the image indeed confirms the clinical findings, the temptation is to declare victory and move on.

The results

These are not just theoretical concerns. In an interesting, and quite alarming, paper titled, “Measuring performance of chest radiography” (Radiology, vol. 217, pp. 456-459, 2000), Dr. E. James Potchen and his colleagues at Michigan State University in East Lansing assessed the performance of more than 100 certified radiologists reading 60 films. When asked “is this film normal?”, there was disagreement among them an average of 20% of the time. This is called “inter-observer variability”. When a single radiologist re-read on a later day the same 60 films, he contradicted his earlier diagnosis 5-10% of the time.

More remarkable, one film of the chest x-rays was of a patient who was missing his left clavicle, or collar bone. Sixty percent of the radiologists failed to identify the missing clavicle! This blindness is not a radiologist’s affliction. Psychologists identified this human tendency to focus on positive data and ignore the negative. You can find this phenomenon in the forensic field, business, and behavioral economics.

What’s to be done?

To the physicians among us, the lesson is don’t succumb to the siren song of gestalt. Look at the whole patient, listen intently to his story, and consider all the possibilities.

To the rest of us who depend on our physician’s judgment, don’t be too timid to ask, have you considered all the possibilities?

Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.

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